# -*- coding: utf-8 -*-
"""
Created on Wed Jul 26 13:33:45 2017

@author: lilin
"""

import sys
from time import sleep

import pygame
from bullet import Bullet
from alien import Alien

def check_keydown_events(event,ai_settings,screen,ship,bullets):
    """响应按键"""
    if event.key==pygame.K_RIGHT:
        ship.moving_right=True
    elif event.key==pygame.K_LEFT:
        ship.moving_left=True
    elif event.key==pygame.K_SPACE:
        fire_bullet(ai_settings,screen,ship,bullets)
    
    elif event.key == pygame.K_q:
        sys.exit()

def check_keyup_events(event,ship):
    if event.key==pygame.K_RIGHT:
        ship.moving_right=False
    elif event.key==pygame.K_LEFT:
        ship.moving_left=False

def check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            sys.exit()
        elif event.type==pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)
        elif event.type==pygame.KEYUP:
            check_keyup_events(event,ship)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mous_x,mous_y = pygame.mouse.get_pos()
            check_play_button(ai_settings,screen,stats,sb,play_button,
                              ship,aliens,bullets,mous_x,mous_y)
            
                        
def check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,
                      bullets,mouse_x, mouse_y):
    """在玩家单机Play时开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)
    if button_clicked and not stats.game_active:
        #重置游戏设置
        ai_settings.initialize_dynamic_settings()
        
        pygame.mouse.set_visible(False)
        #重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True
        
        #重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()
        
        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
        
        #创建一群新的外星人，并让飞船居中
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

            
def fire_bullet(ai_settings,screen,ship,bullets):
    """如果还没有达到限制，就发射一颗子弹"""
    #创建一颗子弹，并将其加入到编组bullets中  
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet=Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)
        
def update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环是都重绘屏幕
    screen.fill(ai_settings.bg_color)
    
    #在外星人和飞船后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    
    #显示得分
    sb.show_score()
    
    #如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()
        
    #让最近绘制的屏幕可见
    pygame.display.flip()
 #-----------------------------------------------------------   
def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """更新子弹的位置，并删除已经消失的子弹"""
    #更新子弹的位置
    bullets.update()
    
    #删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
            
    check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,
                                  aliens,bullets)        


def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,
                                  aliens,bullets):
     """响应子弹和外星人的碰撞"""
     #删除发生碰撞的子弹和外星人
     collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)
     if collisions:
         for aliens in collisions.values():
             stats.score += ai_settings.alien_points * len(aliens)
             sb.prep_score()
             
         check_high_score(stats,sb)   
         stats.score += ai_settings.alien_points
         sb.prep_score()
     
     if len(aliens) == 0:
         #如果整群外星人都被消灭，就提高一个等级
         #删除现有的子弹加快游戏节奏，并创建一群新的外星人
         bullets.empty()
         ai_settings.increase_speed()
         
         #提高等级
         stats.level += 1
         sb.prep_level()
         create_fleet(ai_settings,screen,ship,aliens)
        
 #--------------------------------------------------------       
def get_number_aliens_x(ai_settings,alien_width):
    """计算每行可以容纳多少个外星人"""
    available_space_x=ai_settings.screen_width -2*alien_width
    number_aliens_x=int(available_space_x / (2*alien_width))
    return number_aliens_x

def create_alien(ai_settings,screen,aliens,alien_number,row_number):
    """创建一个外星人并将其放在当前行"""
    alien=Alien(ai_settings,screen)
    alien_width=alien.rect.width
    alien.x=alien_width+2*alien_width*alien_number
    alien.rect.x=alien.x
    alien.rect.y=alien.rect.height+ 2*alien.rect.height * row_number
    aliens.add(alien)
    
def create_fleet(ai_settings,screen,ship,aliens):
    """创建外星人群"""
    #创建一个外星人，并计算一行可以容纳多少个外星人
    #外星人间距为外星人宽度
    alien=Alien(ai_settings,screen)
    number_aliens_x=get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows=get_number_rows(ai_settings,ship.rect.height,alien.rect.height)
    
    #创建外星人群
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings,screen,aliens,alien_number,row_number)
        
def get_number_rows(ai_settings,ship_height,alien_height):
    """计算屏幕可以容纳多少行外星人"""
    available_space_y=(ai_settings.screen_height-
                       (3*alien_height)-ship_height)
    number_rows=int(available_space_y / (2*alien_height))
    return number_rows

def update_aliens(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """检查是否有外星人位于屏幕边缘，并将更新整个外星人的位置"""
    check_fleet_edges(ai_settings,aliens)
    aliens.update()
    
    #检查外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship,aliens):
        ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)
#        print("Ship hit!!!")
    check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets)
    

def check_fleet_edges(ai_settings,aliens):
    """有外星人到达边缘时采取相应的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break
        
def change_fleet_direction(ai_settings,aliens):
    """将整个外星人下移，并改变他们的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1
    
def ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """响应被外星人撞到的飞船"""
    if stats.ships_left > 0:
        #将ship_left减1
        stats.ships_left -= 1
        
        #更新记分牌
        sb.prep_ships()
        
        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
    
        #创建一群新的外星人，并将飞船放到屏幕中央底端中央
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()
    
        #暂停
        sleep(0.5)
    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)
    
    
def check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets):
    """检查是否有外星人到达了屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            #像飞船一样被撞到进行处理
            ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)
            break


def check_high_score(stats,sb):
    """检查是否诞生了新的最高得分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()
        